Circuit and a display using same

ABSTRACT

A circuit of a display comprises a substrate, at least one thin film transistor, at least one first wire and at least one second wire formed on the substrate. The substrate has an active area and a bonding area. The thin film transistor is disposed in the active area. The first wire is disposed in the bonding area. The second wire includes a first end electrically connected to the first wire, a second end electrically connected to the thin film transistor, an overlap portion overlapping the first wire, and a sacrificing portion between the first end and the second end.

This application is a Continuation of co-pending application Ser. No.11/486,025, filed on Jul. 14, 2006, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. § 120 and which claims priority under 35 U.S.C. § 119(a) ofTaiwan Patent Application Serial No. 095105433, filed Feb. 17, 2006, theentire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a circuit of a display, particularly toa circuit used to test or to repair the display.

(2) Description of the Related Art

A pixel array of an active display comprises a plurality of scan linesand data lines cross with each other. Each pixel unit of the pixel arrayemploys a thin film transistor as switch. The source electrode and gateelectrode of the thin film transistor are electrically connected to thedata line and scan line, respectively. When the data line or the scanline is broken, the signal cannot feed through the broken point so theimage quality is worse. That is why a rescue line is employed by adisplay.

Referring to FIG. 1, the display 100 includes an active area 110 and abonding area 120 on the lower substrate 101. The bonding area 120 islocated at the peripheral portion of the active area 110. A sealant 130is applied between the active area 110 and the bonding area 120 or atthe peripheral portion of the active area 110 to adhere the lowersubstrate 101 to the upper substrate (not shown). The active area 110 isdisposed with a plurality of scan lines 112, data lines 114 and thinfilm transistors 115. The bonding area 120 is disposed with a datadriver 128 electrically connected to the data line 114, and with a scandriver 129 electrically connected to the scan line 112. Three shortingbars 122, 124, 126 disposed at one side of the bonding area 120 areelectrically connected to the red, blue, green pixels and the testdevice (not shown) to find the defect. After testing, the shorting bars122, 124 and 126 are cut along C-C line by laser.

In the prior art, the rescue line 116 encloses the active area 110 aloneinner side of the sealant 130, but does not connect to the shorting bars122, 124 and 126. The repairing by the rescue line 116 is described asfollows. In the normal state, the rescue line 116 overlaps butelectrically insulated from the data line 114 or the scan lines 112 viaan insulating layer (not shown). If the data line 114 has a broken point117, then the data driver 128 cannot transmit the data signal into thepixel unit 102 through the path A. Under the circumstances, theinsulating layer of the welding point 103 a and 103 b is welded forconducting the rescue line 116 with the data line 114. Therefore, thedata signal can transmit along the path B, that is, the signal goes tothe welding point 103 a, and then turn to the rescue line 116,subsequently, it goes to the welding point 103 b, and is input to thethin film transistor 115 of the pixel unit 102 through the other end ofthe data line 114.

However, if a break point 118 is generated in the region 140 which islocated outside the rescue line 116, the rescue line 116 will be out ofaction because the data signal cannot be transmitted into the rescueline 116. The reasons are as following:

1. Currently the rescue line 116 is disposed inside the sealant 130, sothe defects, such as pad burn or lead scratch etc., occurring in theregion 140 outside the rescue line 116 cannot be repaired. That causesthat the display products, such as TV, are frequently discarded in thelatter manufacturing process or in client end.

2. The rescue line 116 is separated from the test lines 122, 124 and 126to reduce the utilization ratio of the substrate.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a circuit of adisplay, which combines a rescue line with a test line to reduce thefailure of the display and to increase the utilization ratio of thesubstrate.

In one aspect of the present invention, the circuit of a displaycomprises a substrate, at least one thin film transistor, at least onefirst wire and at least one second wire formed on the substrate. Thesubstrate has an active area and a bonding area. The thin filmtransistor is disposed in the active area. The first wire is disposed inthe bonding area. The second wire includes a first end electricallyconnected to the first wire, a second end electrically connected to thethin film transistor, an overlap portion overlapping the first wire, anda sacrificing portion between the first end and the second end.

The overlap portion can be welded selectively and the sacrificingportion can be cut selectively. If the overlap portion has been notwelded and the sacrificing portion has been not cut yet, the circuitcould use to test the display for finding defects. After testing, thesacrificing portion is cut. If the wire of the display is failure, theoverlap portion will be welded, at that time, the circuit structure isserved as a rescue line.

The present invention can save the arranged area of the rescue line, andchange a non repair area into a repair area. Besides, the failure can bereduced due to less pad burn or lead scratch in TV products.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be specified with reference to itspreferred embodiment illustrated in the drawings, in which

FIG. 1 shows a plane diagram of a circuit with a rescue line in adisplay according to the prior art;

FIG. 2 shows a circuit structure applied to a display according to thepresent invention;

FIG. 3 shows a sectional view of the overlap portion in the circuitstructure according to the present invention;

FIG. 4 illustrates a testing process of the display according to thepresent invention; and

FIG. 5 shows a sketch diagram illustrating how to repair the displayaccording to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 2, the display 200 includes a substrate 210 dividedinto an active area 212 and a bonding area 214. A pixel array 211 isdisposed in the active area 212 and is covered by an upper lid (notshown) and a color filter (not shown). The sealant 216 encloses theactive area 212 for adhering the substrate 210 to the upper lid or thecolor filter. A data driver 201, a scan driver 203, at least one firstwire 204 and at least one second wire 220 are disposed in the bondingarea 214. The first wire 204 is electrically connected to the testdevice (not shown).

The pixel array 211 includes a plurality of thin film transistors 202.Each of the thin film transistors 202 is disposed on the substrate inthe active area 212 and electrically connected to the data driver 201through the data line 205, and electrically connected to the scan driver203 through the scan line 207. It is noted that the second wire 220 hasone end 222 electrically connected to the first wire 204, and the otherone end 224 electrically connected to the thin film transistor 202through the data driver 201. An overlap portion 226 and a sacrificingportion 228 are disposed between two ends 222 and 224. The overlapportion 226 overlaps the first wire 204. The sacrificing portion 228 isa predetermined region of the substrate for cutting along the C-C line.

Preferably, the sacrificing portion 228 is located between the overlapportion 226 and the end 222. The overlap portion 226 is electricallyconnected to the first wire 204. The sacrificing portion 228 cooperateswith the first wire 204 to form a ring structure.

Referring to FIG. 3, the insulating layer 250 includes a contact hole252 disposed between the overlap portion 226 and the first wire 204.When the contact hole 252 is welded by a laser, the first wire 204 iselectrically connected to the second wire 220. The contact hole 252 canbe made from the metal or conductive materials. The insulating layer 250is made of silicon nitride (SiNx), gate silicon nitride (g-SiNx),amorphous silicon (a-Si) or etching stopper silicon nitride (ES-SiNx).By the way, there is no limitation about the relative position betweenoverlap portion 226 and the first wire 204 in the present invention. Inother words, the first wire 204 can be also disposed below the secondwire 226.

In testing process of the display 200, the first wire 204 and the secondwire 220 can act as test lines. When the data line 205 or the scan line207 is failed, the first and second wires 204 and 220 can act as rescuelines. Two embodiments are provided as follows.

Referring to FIG. 4, three first wires 204 a, 206 a and 208 a aredisposed in the bonding area of the substrate 210 and electricallyconnected to a test device 300, which is formed as a multi-jump controlcircuit (MJC), to test the red pixels R, green pixels G and blue pixelsB of the display 200.

The first wire 204 a is electrically connected to a plurality of secondwires 220, and then electrically connected to all red pixels R of thedisplay 200. Likewise, the first wire 206 a is electrically connected toa plurality of second wires 230. By way of the second wires 230, thefirst wire 206 a can be electrically connected to all green pixels G ofthe display 200. The first wire 208 a is electrically connected to aplurality of second wires 240. By way of the second wires 240, the firstwire 208 a is electrically connected to all blue pixels B of the display200.

For convenience, the first wire 204 a electrically connected to the redpixel R is referred to as “first red wire 204 a”, and the second wire220 electrically connected to the red pixel R is referred to as “secondred wire 220”. Following the analogy of this, the first wire 206 aelectrically connected to the green pixel G is referred to as “firstgreen wire 206 a”. The first wire 208 a electrically connected to theblue pixel B is referred to as “first blue wire 208 a”. The second wires230 and 240 are referred to as “the second blue wire 230” and “thesecond green wire 240”.

The process for testing the red pixels R is described as follows. Beforetesting, the sacrificing portion cannot be cut, and the overlap portion226 is electrically insulated from the first red wire 204 a, thesectional view is shown in FIG. 3. It is unnecessary to limit therelative position between the overlap portion 226 and the first wire 204a. In other words, the first wire 204 a can be disposed below the secondwire 220. The insulated layer (not numbered) without contact hole 252 isdisposed between the first wire 204 a and the overlap 226. When startingto test, the first wire 204 a is electrically connected to the testdevice 300.

The method for testing circuit is described as follows. The test device300 provides a test signal to the first red wire 204 a. And then thetest signal is transmitted to the thin film transistors 202 of all thered pixel R through the second red wire 220. As arrows, the detailpathway is that test signal is transmitted to the thin film transistor202 by way of the test device 300, the first wire 204 a, the end 222 ofthe second wire 220, the sacrificing portion 228, the overlap portion226, the other end 224 of the second red wire 220, the data driver 201.Likewise, the test device 300 just provides test signals to the firstwire 206 a and 208 a, so that the green pixels G and blue pixels B canbe tested by the same way.

Besides connecting to the test device 300, the first red wire 204 a, thefirst green wire 206 a and the first blue wire 208 a are alsoelectrically connected to a printed circuit board 400 for repairing.

Referring to FIG. 5, the substrate 210 is structured under two sectionsfor illustration. After testing the display 200, the sacrificing portion228 has been cut by laser. The first red wire 204 a, the first greenwire 206 a and the first blue wire 208 a are electrically connected tothe printed circuit board 400, and then electrically connected to theauxiliary line 2042 in the active area 212. When the data line 205 isfailed, such as broken point 260, data signals cannot be input to thecolumn of red pixels R along the data line 205. Under the circumstances,the contact hole (not numbered) can be welded so that the data signalscan be input to the column of red pixels R by way of the second red wire220, first wire red wire 204 a, the print circuit board 400, theauxiliary line 2042, the welding point 2041 in sequence.

A point worth emphasizing, the present invention can be also applied torepair the failure occurs in the region between the active area 212 andthe data driver 201. Besides, it makes the rescue line cover less areaof the active area 212.

The present invention can be applied to repair the data lines or thescan lines. The arrangement of the pixel units is not limited to whatshown in the figures. The first wire can be a shorting bar. The secondwire can be a hook-type wire. The data driver 201 or the scan driver 203can be packaged to a flexible board with chip-on-film (COF) or tapeautomated bonding (TAB). The printed circuit board can be replaced withan external circuit. It is means that the first wire is electricallyconnected to the external circuit, and then the external circuit iselectrically connected to the thin film transistor with COF or TAB toform a whole repair cycle.

While the preferred embodiments of the present invention have been setforth for the purpose of disclosure, modifications of the disclosedembodiments of the present invention as well as other embodimentsthereof may occur to those skilled in the art. Accordingly, the appendedclaims are intended to cover all embodiments which do not depart fromthe spirit and scope of the present invention.

1. A circuit for use in a display, comprising: a substrate having anactive area and a bonding area; at least one thin film transistordisposed on the substrate and in the active area; at least one firstwire disposed on the substrate and in the bonding area; and at least onebroken second wire including: a first end electrically connected to thefirst wire; a second end electrically connected to the thin filmtransistor; an overlap portion overlapping the first wire; and a breaklocated between the first end and the overlap portion so that the firstend and the second end are not electrically connected.
 2. The circuit ofclaim 1, wherein the first wire is electrically connected to an externalcircuit.
 3. The circuit of claim 1, wherein the overlap portion iselectrically insulated from the first wire.
 4. The circuit of claim 1,wherein the overlap portion is electrically connected to the first wire.5. The circuit of claim 1, further comprising an insulating layerdisposed between the overlap portion and the first wire, wherein theinsulating layer is comprised of silicon nitride, gate silicon nitride,amorphous silicon, or etching stopper silicon nitride.
 6. The circuit ofclaim 1, further comprising an insulating layer disposed between theoverlap portion and the first wire, wherein the insulating layer has acontact hole for electrically connecting the first wire and the overlapportion.
 7. The circuit of claim 1, wherein the second wire is anhook-type wire.
 8. The circuit of claim 1, wherein the first wireincludes a first red wire connecting to a first red pixel, a first greenwire connecting to a first green pixel, and a first blue wire connectingto a first blue pixel.
 9. A circuit for use in a display, comprising: asubstrate having an active area and a bonding area; at least one thinfilm transistor disposed on the substrate and in the active area; atleast one first wire disposed on the substrate and in the bonding area;at least one second wire, each having: a first end electricallyconnected to the first wire; and a second end substantially located atan edge of the substrate; and at least one third wire, each having: afirst end substantially located at the edge of the substrate; and anoverlap portion overlapping the first wire.
 10. The circuit for use in adisplay of claim 9, wherein the overlap portion is electricallyinsulated from the first wire.
 11. The circuit for use in a display ofclaim 9, wherein the overlap portion is electrically connected to thefirst wire.
 12. The circuit for use in a display of claim 9, furthercomprising an insulating layer disposed between the overlap portion andthe first wire, wherein the insulating layer is comprised of siliconnitride, gate silicon nitride, amorphous silicon, or etching stoppersilicon nitride.
 13. The circuit for use in a display of claim 9,further comprising an insulating layer disposed between the overlapportion and the first wire, wherein the insulating layer has a contacthole for electrically connecting the first wire and the overlap portion.14. The circuit for use in a display of claim 9, wherein the second wireis an hook-type wire.